India - Bombay Sewage Disposal Project : environmental assessment (Vol. 1 of 4) : Executive summary : marine outfalls

* _ 0 - :e - a a . ':'''',. - "'-- -' '"S...'. :.--'-'. -"-"'""'' ." .. t O ............... S . . . . . . h. 1< >> fff 0: ; e :;St 0- t- ^<;9ED X tit1 r - -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~........ .... . ;; ::-:- n ->z-S!~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~.... . 0-4 --~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~. .-....,..-- ..:. { _~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ . --. . .. . . . J.-.--.  C E X E C U T I V E S U M M A R Y fs BOMBAY SEWAGE DISPOSAL PROJECT MARINE OUYFAhhS SPONSOR MUNICIPAL CORPORATION OF GREATER BOMBAY NATIONAL ENVIRONMENTAL ENGINEERING RESEARCH INSTTUTE  CONTE: .f . Page No. UST OF FIGURES ii UST OF TABLES iii PREAMBLE 1 BOMBAY SEWAGE DISPOSAL PROJECT 1 THE PROPOSED FACIUTIES NEED FOR PRESENT STUDY 2 OBJECTIVES OF ENVIRONMENTAL ASSESSMENT 2 ENVIRONMENTAL STANDARDS 3 METHODOLOGY FOR ENVIRONMENTAL ASSESSMENT 3 EXISTING ENVIRONMENTAL STATUS 4 ENVIRONMENTAL IMPAS OF PROOSED PROJECT 6 ANALYSIS OF ALTERNATIVES 8 MITIGATION PLAN 9 RECOMMENDATIONS 10 PUBLIC PARTICIPATION 1 0 ENVIRONMENTAL MONITORING I 1 INSTITUTIONAL NEEDS 12 APPENDIX I - TABLES - 13-1k APPENDIX 11 - FIGURES 19-25 lS}it 1l UY SEVION IllO IL- PROJECT  LIST OF FIGURES Figure 1 : Drainage Zones and Treatment/ Disposal Schemes Fgure 2 : Present Microbial Quality at'Reference Line Figure 3 : Present DO levels at Reference Line Figure 4 Total Coliforn Scenarios for 3 km Long Outfalls (Nonmonsoon) Figure S Total Coliform Scenarios for 3 km Long Outills (Monsoon) rigure 6 Total Coliform Scenarios for 5 km Long Outfalls (Nonmonsoon) figure 7 : Total Coliform Scenarios for 5 km Long Outfa Its (Monsoon) fIMIA %EWM;E DIS'OSAL IROIEC.r OUTFALLS  LIST OF 1ABLES Table I : Sizes and Specifications of Proposed Outfalls Table 2 : Tolerance Limits for Water Quality After Receiving Discharges Table 3 : General Standards fbr Discharge of Effluents Table 4 : Mitigation Plan for Construction and Operational -Impacts of Marine Outfalls HOKUMY SEVWXE 12ISICJSAL IROCIECr SUIFALLSHi  BOMBAY SEWAGE PREAMBLE DISPOSAL PROJECT 1. Bombay is the hub of commercial and industrial activities and has witnessed a rapid growth during past few decades. Executive Summary According to 1991 census, 9.93 millioni persons reside within the municipal limits of Greater Bombay which has a land area-df 603 sq. kilometers. 2. The infrastructural development, however, has not kept pace with the growth of population. As a result, the city suffers from shortage of all basic amenities including housing water supply, sanitation and transport. Amongst these, sanitation is perhaps the most neglected-sector. Out of approximately 1 500 mid, only a miniscule proportion 22.5 mid (11.5%) of municipal wastewater generated in the city receives treatment before disposal to adjoining coastal and creek regions. Discharge of such large quantity of untreated sewage into the coastal environment has resulted in widespread impairment of coastal water quality. BOMBAY SEWAGE DISPOSAL PROJECa 3. The first integrated wastewater management scheme for the city was planned in 1970. The scheme envisaged disposal of screened wastewater from entire Bombay municipal area through two submarine outfal Is at Wbrli and Bandra. 4. The plan, since then has undergone many revisions. The most recent Development Plan Ill, divides the Bombay municipal region into seven drainage areas. The plan prrvides for disposal of wastewater after preliminary treatmtrn through manrne outfalls at Colaba, Wbrli and Bandra into) clia'%i .-.- For the remaining four drainage zunes vreamlwlnt in. t-r.rd I.a ,xin's proposed before effluent disp^ul andc. te- .md1.Cent crek% (Figure 1). THE PROPOSED FACILITIES Marine Outfafts 5. Under Bombay Sewage Disposal Project, two 3 kilomneters lung outfalls are proposed to) dispose of the wastewaters fruini Au,rli and Bandra drainage areas into the sea after preliminiary treatimient. Salient design features for the tw) opticn% ari provided in Table 1. 6. The headworks for the outfalls will comprise influent puilipingh stations; preliminary treatnent facilities comprising coarse and C)0MILY %E%sWu,E DISlPOSAL PROJECT DJffALLS  E X E C I T I V E fine screens and grit removal; and effluent purnring stati0n to S U U M A a Y provide the motive force for wastewater disposal against the tide. NEED FOR PRESENT STUDY 7. The present study has been undertaken in keeping with the World Bank policy and procedure for the environmental assessment of Bank lending operations with respect to Bombay Sewage Disposal Project-Development Plan ill. Procedures as listed under Operational Directive 4.01 have been followed during the assessment. The study also meets the requirements of State of Maharashtra and Government of India for environmental clearance of development projects. OBJECrIVES OF ENVIRONMENTAL ASSESSMENT 8. As a pollution abatement scheme, Bombay Sewage Disposal Project is expected to achieve an appreciable degree of improvement in the coastal water quality. The project shall, therefore, mainly have beneficial impacts on the environment. The primary objective of the environmental assessment study has been to ascertain if the proposed facilities are adequate to - provide the desired benefits and if not, what modificaticons in the form of higher degree of treatment and/or increase in outfall lengths would be necessary. The implementation of the project, however, involves large scale construction activities. The study, therefore, also aimed at assessment of the potential negative impacts du.ring the constructions of the project and delineation of necessary mitigatory measures. 9. With the above objectives, the study was planned to evaluate following issues: * Adequacy of proposed outfalls at Bandra and A&brli for compliance with stipulated standards at the reference line * Need for and nature oi augmentation ot proposed sschenies fiur compliance with tile standards * Assessment of adverse impacts due to constructiol- .of tIhe facilities and delineation ot mitigatory measures * Assessment of impacts otf operation of marine (JutTalls on aquatic ecosystem with respect to dissolved oxygen. tiLitrie it enrichment and accumulation of metals in 'iediiiients * Assessnment of socio-econromic impacts of tte project. I;tDFSAN. %E%%:U;E DISUTF AL PROJCT 0UTFALLS -  X X E X U T I V E ENVIRONMENTAL STANDARDS 3AMM AIY 10. Environment (Protection) Act, 1986 vests in Central Government, the powers to lay down standards for environment protection.. Central and State Pollution Control Boards are responsible for compliance of these standards. The Boards, based on local conditions, have power to stipulate more stringent location specific standards. 11. For protection of coastal water quality, two standards apply in India. The first of these standards is in the form of receiving water. quality and is based on best designated use of the water body such as for bathing, fishing or navigation. Pertinent details of these standards (15:7967-1976) are provided in Table 2. The creek and coastal waters used for recreational purpoises or fishing, accordingly, should always have biochemical oxygen demand (BOD) less than 5.0 mg/L, total coliormns not more than 1000/100 ml and dissolved oxygen (DO) more than 3.a mg/ L. 12. The second standard is in the form of effluent standards for discharges into marine coastal area. Accordingly to the standards has summarized in Table 3, effluents with BOD and suspended solids of .100 mg/ L each and ammoniacal nitrogen upto 50 mg/ L can be discharged into the creeks. 13. No effluent standard, however, has been stipulated for coastl discharges through marine outfalls. In the absence of such standard, Maharashtra Pollution Control Board (MPCB) has given consent to MCGB for discharging treated/untreated sewage subject to compliance of receiving water quality standard for coastal waters viz. total coliform counts less than I 000 / 1 00 ml. Since the outfall discharges on their movement towards the coast can pollute the beaches etc., it has been further stipulated by MPCB that compliance with the receiving water standards shall be measured at 1 kiloineter Trnomi the coastlinel 2, This standard, based on the findings of this stuidy. was viewed to he top stringent by MPCB and have amencled the latest consent suitably. METHODOLOGY FOR ENVIRONMENTAL ASSESSMENT 14. In order to assess improvement in coastal water quality, its existing status was determined through elaborate field surveys. The surveys were conducted during winter of 19 91 and suminer of of 1 992. During the surveys 220 water and sediments samples along 24 kilometers of Bumbay's coast were collected. The 1. * Ih.o ..tly W.i4 .utquil.dlhn the. -.inI.iu WO QiiI in ha,.. the urK4ImnIi.'aV .an1 ItJ.. as. th.J~ ,h111 1 6.4.1 Ia st. ftl ai4,. Iha. blina ii.t1ii I .ll% hiAw . dw 1- IrWrta .tH .iuI I th- %he. ,uIkI.d.- - :L tg.u